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Short-circuit empty objects/arrays

This commit is contained in:
John Keiser 2020-08-03 09:36:18 -07:00
parent 64cf18aa1e
commit 70c2a1c9f9
1 changed files with 54 additions and 21 deletions
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75
src/generic/stage2/structural_parser.h
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@ -84,6 +84,30 @@ struct structural_parser : structural_iterator {
end_scope(internal::tape_type::ROOT, internal::tape_type::ROOT);
}
really_inline void empty_container(internal::tape_type start, internal::tape_type end) {
auto start_index = next_tape_index();
tape.append(start_index+2, start);
tape.append(start_index, end);
}
WARN_UNUSED really_inline bool empty_object() {
if (peek_next_char() == '}') {
advance_char();
log_value("empty object");
empty_container(internal::tape_type::START_OBJECT, internal::tape_type::END_OBJECT);
return true;
}
return false;
}
WARN_UNUSED really_inline bool empty_array() {
if (peek_next_char() == ']') {
advance_char();
log_value("empty array");
empty_container(internal::tape_type::START_ARRAY, internal::tape_type::END_ARRAY);
return true;
}
return false;
}
// increment_count increments the count of keys in an object or values in an array.
// Note that if you are at the level of the values or elements, the count
// must be increment in the preceding depth (depth-1) where the array or
@ -261,10 +285,13 @@ WARN_UNUSED static really_inline error_code parse_structurals(dom_parser_impleme
// Read first value
//
switch (parser.current_char()) {
case '{':
case '{': {
if (parser.empty_object()) { goto finish; }
SIMDJSON_TRY( parser.start_object(false) );
goto object_begin;
case '[':
}
case '[': {
if (parser.empty_array()) { goto finish; }
SIMDJSON_TRY( parser.start_array(false) );
// Make sure the outer array is closed before continuing; otherwise, there are ways we could get
// into memory corruption. See https://github.com/simdjson/simdjson/issues/906
@ -274,6 +301,7 @@ WARN_UNUSED static really_inline error_code parse_structurals(dom_parser_impleme
}
}
goto array_begin;
}
case '"': SIMDJSON_TRY( parser.parse_string() ); goto finish;
case 't': SIMDJSON_TRY( parser.parse_root_true_atom() ); goto finish;
case 'f': SIMDJSON_TRY( parser.parse_root_false_atom() ); goto finish;
@ -291,25 +319,27 @@ WARN_UNUSED static really_inline error_code parse_structurals(dom_parser_impleme
// Object parser states
//
object_begin:
switch (parser.advance_char()) {
case '"': {
parser.increment_count();
SIMDJSON_TRY( parser.parse_string(true) );
goto object_key_state;
}
case '}':
parser.end_object();
goto scope_end;
default:
if (parser.advance_char() != '"') {
parser.log_error("Object does not start with a key");
return TAPE_ERROR;
}
parser.increment_count();
SIMDJSON_TRY( parser.parse_string(true) );
goto object_key_state;
object_key_state:
if (unlikely( parser.advance_char() != ':' )) { parser.log_error("Missing colon after key in object"); return TAPE_ERROR; }
switch (parser.advance_char()) {
case '{': SIMDJSON_TRY( parser.start_object(false) ); goto object_begin;
case '[': SIMDJSON_TRY( parser.start_array(false) ); goto array_begin;
case '{': {
if (parser.empty_object()) { break; };
SIMDJSON_TRY( parser.start_object(false) );
goto object_begin;
}
case '[': {
if (parser.empty_array()) { break; };
SIMDJSON_TRY( parser.start_array(false) );
goto array_begin;
}
case '"': SIMDJSON_TRY( parser.parse_string() ); break;
case 't': SIMDJSON_TRY( parser.parse_true_atom() ); break;
case 'f': SIMDJSON_TRY( parser.parse_false_atom() ); break;
@ -347,17 +377,20 @@ scope_end:
// Array parser states
//
array_begin:
if (parser.peek_next_char() == ']') {
parser.advance_char();
parser.end_array();
goto scope_end;
}
parser.increment_count();
main_array_switch:
switch (parser.advance_char()) {
case '{': SIMDJSON_TRY( parser.start_object(true) ); goto object_begin;
case '[': SIMDJSON_TRY( parser.start_array(true) ); goto array_begin;
case '{': {
if (parser.empty_object()) { break; };
SIMDJSON_TRY( parser.start_object(true) );
goto object_begin;
}
case '[': {
if (parser.empty_array()) { break; };
SIMDJSON_TRY( parser.start_array(true) );
goto array_begin;
}
case '"': SIMDJSON_TRY( parser.parse_string() ); break;
case 't': SIMDJSON_TRY( parser.parse_true_atom() ); break;
case 'f': SIMDJSON_TRY( parser.parse_false_atom() ); break;